This specification relates to lasers, optical transmitters and optical transceivers and their applications in optical communications based on wavelength division multiplexing (WDM).
Various optical fiber transmission systems use optical WDM transceivers to transmit and receive data by combining a number of different optical channels or signals at different WDM wavelengths onto a single fiber. Light at these WDM wavelengths is modulated as optical signals at different WDM wavelengths to carry data of different signals, respectively. For example, an optical fiber transmission system can be designed to include n number of optical WDM channels each with a data rate of m Gb/s to transmit through a single fiber with data throughput rate at n×m Gb/s. As such, data transmission at a data throughput rate of 100 Gb/s can be achieved by using, for example, 10 optical WDM channels each at a channel data rate of 10 Gb/s or 4 optical WDM channels each at a channel data rate of 25 Gb/s. To achieve a sufficiently high data throughput rate at n×m Gb/s, the number of optical WDM channels, n, can be increased to reduce the data rate m per optical channel to advantageously use relatively matured low-data-rate optical WDM technologies and the associated CMOS electronic technologies for the electronic driver and data processing circuits.
Optical WDM transceivers can be in various configurations where each transceiver includes a transmitter part that transmits one or more optical WDM signals and a receiver part that receives one or more optical WDM signals. An integrated multi-wavelength WDM transceiver is a transceiver in a compact platform that allows multiple streams of data to be simultaneously placed on a single physical input and output (I/O) port using multiple optical WDM wavelengths from an array of lasers operated at the optical WDM wavelengths. Such integration offers a number of advantages including low power operation, spatial and cost efficiency, improved system reliability, and operational simplicity. In various optical WDM systems, integrated Coarse WDM (CWDM) or Dense WDM (DWDM) compact form pluggable (CFP) transceivers can be used to offer an economical and power-efficient way to implement 100-Gb/s transmission on a single fiber by an array of CWDM or DWDM lasers, each transmitting at 10 Gb/s or 25 Gb/s aligning with CMOS electronic drive speeds.